Size alone tells youA small JPEG lives inside every NEF, CR3 and ARW, put there to give the camera something for the back screen. An ordinary tool takes that, marks the RAW recovered, then moves along to the next file. Which is why a 50MB frame gets home at 5MB.
Large files seldom sit in one runAn unbroken run of free space long enough for a large file is rare on a card. At the first gap it reaches, a basic carver stops, which costs you a corner of a JPEG and the entirety of a RAW or a clip. The order the runs go in is recorded within the file format itself, and knowing how to read that is where the difference lies.
Each RAW format gives way in its own mannerUnderneath CR2 is TIFF, and that is why it survives damage reasonably well. CR3 uses a newer container built on other principles. In a NEF, damage tends to appear as green and purple banding across the frame. As for ORF, RAF, RW2, ARW and DNG, every one of them wants handling on its own terms, and nothing bought off a shelf covers the lot.
What a deletion really removesA deletion on FAT or exFAT releases the cluster chain a file was using; a format releases them all together. Nothing at all gets wiped off the card, which is the reason recovery works — and equally the reason your very next exposure may be written straight across the picture you wanted.